Radio frequency (“RF”) energy, also known as electromagnetic energy, is used in a wide range of applications. Systems employing RF energy may include, for example, a source and a load receiving RF energy from the source. Some systems use the RF energy to heat a material. In such systems the load may be in the form of a susceptor that converts the RF energy to heat. Further, such systems often use electromagnetic energy at microwave frequencies.
Matching the output impedance of the source with the input impedance of the load may provide efficient transfer of RF energy to the load. When the impedances are mismatched, RF energy is reflected back from the load to the RF source. However, such impedance matching may be difficult to implement in systems having a load with an unknown and/or time varying impedance.
In systems where the load impedance is unknown or varies with time an isolator may be used between the RF energy source and the load to prevent the reflected energy from returning to the source. However, when the mismatch is mitigated with such an isolator, the reflected RF energy is dissipated in a local dummy load and, thus, is wasted. In high power systems, the dissipation of this wasted power may be substantial and give rise to cooling issues that may increase the cost of manufacturing and operating the system.